Fenton’s oxidation as post-treatment of a mature municipal landfill leachate

Mature landfill leachates contain some macromolecular organic substances that are resistant to biological degradation. Recently, Fenton’s oxidation has been investigated for chemical treatment or pre-treatment of mature landfill leachates. The aim of this study was to reduce the recalcitrant organic load still remaining after the complete treatment of a mature landfill leachate by Fenton’s oxidation post-treatment. The effect of various parameters such as H2O2 to Fe2+ molar ratio, dosage of Fe2+ reagent, initial pH, reaction time and initial chemical oxygen demand (COD) strength, that have an important role on the oxidation, was analysed. A molar ratio H2O2/Fe2+ = 3, a Fe2+ dosage of 4 mmol·L−1, pH 3, and a reaction time of 40 min were found to achieve better oxidation performances. At these favorable conditions, COD removal efficiency was 60.9% and 31.1% for initial COD of 93 and 743 mg·L−1 respectively (diluted and non diluted leachate). Fenton’s oxidation also presented good results for color removal. In spite of being extremely difficult to treat this leachate, the above results seem rather encouraging on the application of Fenton’s oxidation.This work was supported from Fundação para a Ciência e Tecnologia through the grants SFRH/BD/24715/2005 and SFRH/BPD/26803/2006. S. Cortez, P. Teixeira, R. Oliveira* and M. Mota are with Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710 – 057 Braga, Portugal (*corresponding author, phone: +351-253604409; fax: +351-253678986; email: roliveira@deb.uminho.pt)